Introduction The revealing of leaves structural peculiarities in Cydonia x Malus distant hybrids which distinguish after genotype and resistance to biotic and abiotic factors represent an interest for deeply knowing the biological properties of the hybrid forms which is actual for pomiculture. The peculiarities of epidermal leaf structure of tetraploid hybrids, quince x apple, which grows and develop at the Botanical Garden (Institute) of ASM in this paper are described. The differences, qualitative and quantitative, of the epidermal leaf in 7 Cydolus hybrid forms, in comparison with genitors and other hybrid plants are emphasized. Results and discussions Hypo-stomatal leaf at tetraploid hybrids which in the present research were included has a dorsiventral structure like to those initial forms. Epidermal tissue the mesophyll envelop, which the superior adaxial and, inferior abaxial epidermis form. Adaxial epidermis from a single row of fl at cellule is compound; they are tangentially elongated with rectilinear contour and compactly situated. Abaxial epidermal cells from those of adaxial epidermal cell after form, dimension, and thickness of cell membrane and of cuticle are distinguished. Abaxial epidermal leaf of hybrid plants studied, as well as initial forms, of many components is compound, so epidermal nomophylle cells of polygonal form, which possess a sinusoidal profi le; stomata which are formed from two reniform stomatal cells positioned tête-á-tête; annex cells and hairy-leaved of different form and size. The stomata, together with secondary cells, stomatal complex of apomixis type are formed. Tetraploid hybrids from the diploid and triploid plants by epidermal cells of lager dimensions both in radial direction (45-50 μm), and in that of tangential (25-29 μm) are distinguished. The medium length of leaf epidermal cells at the diploids was 23-37 μm, while the width varies between 14 and 22 μm; the length of cells at parental forms reached 34-38 μm, and their width achieve 19 to 24 μm. The triploids, after the above-mentioned parameters an intermediate position between tetraploid and diploid occupy [1]. This regularity at the studied hybrids concerning such anatomical characters as the stomata and aperture dimensions were identifi ed. The study results confi rmed on the existence of direct correlative dependence (r= 0,6-0,8) between the polyploid level at the intergeneric hybrids, quince x apple, and the dimensions cells epidermis adaxial and abaxial of stomata and ostiole. However, a correlative indirectly proportional dependence into the multiplicity level and stomatal frequency of epidermal abaxial and adaxial cell per unit of foliar area (r= 0,5-0,6) is registered. Stomatal density per 1 mm2 of foliar area at tetraploid was 357-420, diploid – 471-663, triploid – 419-551, meantime at apple was equal to 716 and quince – 855.